Milltek-800
You probably needed a new exhaust anyway, £800 for a full system like the Milltek is about average, you can do it cheaper but you can also spend a lot more. I have NEVER seen anyone on here say that changing the exhaust makes any benefits in power.
upRev-480
Probably the best money you can spend on a Zed, it totally transforms the throttle response and mis range torque, it isn't always about numbers. Also you spent so much because you got an upRev before you got everything sorted so had to remap twice, so more dyno time...
Plenum spacer-150
Could be argued does not do a lot without an upRev, but if you are going to get a map you might as well get the best out of the engine you can.
JWT pop charger-100
Well documented on here that this loses you BHP in general so not sure why you bolted one on, maybe you enjoy the sound in which case why moan about dyno results?
Berk HFC's-370
Again purely for noise, if you wanted more BHP you should have spent it on a better Ypipe (XYZ?) or got decats possibly.
Ams pulleys-180
When I saw these on here I did a bit of research and was told by someone I respect that this would be a complete waste of time and money....
Conclusion
Just my thoughts, not having a pop just adding a bit of perspective, you clearly are not impressed with spending £2k on a NA engine and not getting any 'results' but 5 minutes searching on here would have told you that and saved you £2k if bragging rights were all you wanted...